Summary: Cardiac failure incurs a major economic and social burden on the United States populace, while also providing a distinct technical challenge since options for treating this condition remain highly limited. In ischemic cardiomyopathy ventricular wall thinning is coupled with dilation of the ventricular cavity. This remodeling process is associated with elevated ventricular wall stress that positively drives the thinning and dilation process towards end-stage heart failure. In the proposed work we will create novel designs for injectable biomaterials to bulk the thinning, post-infarct cardiac wall, reducing elevated wall stress, and potentially improving cardiac remodeling outcomes. The design objectives include synthesizing materials with tensile properties suitable for reducing wall stresses, degradation properties that maintain the hydrogel in the infarcted wall for a period of months during the remodeling process, and drug delivery properties that allow the controlled release of multiple growth factors that may stimulate beneficial cardiac remodeling. We will evaluate 3 distinct hydrogel designs with increasing complexity, utilizing both rat and porcine models of ischemic cardiomyopathy and a minimally invasive robotic technology (the HeartLander device) designed to effectively deliver the targeted hydrogel injections. The project specific aims are to: 1) Evaluate the functional and histopathologic effect of injecting the thermoresponsive hydrogel, poly(NIPAAm-co-acrylic acid-co-2-hydroxyethyl methacrylate-poly(trimethylene carbonate) into the central and border regions of a myocardial infarct in a porcine model for ischemic cardiomyopathy using a modified HeartLander minimally invasive robotic system. 2) Evaluate the functional and histopathologic effect of injecting the thermoresponsive hydrogel, poly(NIPAAm-co-HEMA-co-polylactide-methacrylate) into the central and border regions of a myocardial infarct in rat and then porcine (with HeartLander) models for ischemic cardiomyopathy. Hydrogel design optimization will be based on in vitro and rat in vivo results. 3) Develop and characterize the thermoresponsive hydrogel poly(NIPAAm-co-N-hydroxysuccinimide- methacrylate-co-HEMA-co-MAPLA) and the ability of this gel to deliver bFGF in vitro, as well as the ability to load this gel with microspheres containing IGF-1 for more extended controlled release. 4) Evaluate the functional and histopathologic effect of injecting growth factor loaded hydrogel from Aim #3, into infarcted myocardium in rat and porcine (with HeartLander) models for ischemic cardiomyopathy. Relevance: Once the early period following a heart attack passes, there are limited options for treating the heart failure that can develop. At the end of the proposed funding period we will have developed innovative injectable materials to treat heart failure following a heart attack as well as a robotic delivery system to allow material delivery in a manner that would minimize patient discomfort, complications and recovery time.